1. Field of the Invention
The present invention relates to nanostructures and, more specifically to patterned nanostructures.
2. Description of the Prior Art
Binary semiconducting oxides often have distinctive properties and can be used as transparent conducting oxide (TCO) materials and gas sensors. Current studies of semiconducting oxides have been focused on two-dimensional films and zero-dimensional nanoparticles. For example, fluorine-doped tin oxide films are used in architectural glass applications because of their low emissivity for thermal infrared heat. Tin-doped indium oxide (ITO) films can be used for flat panel displays (FPDs) due to their high electrical conductivity and high optical transparency; and zinc oxide can be used as an alternative material for ITO because of its lower cost and easier etchability. Tin oxide nanoparticles can be used as sensor materials for detecting leakage of several inflammable gases owing to their high sensitivity to low gas concentrations.
In contrast, investigations of wire-like semiconducting oxide nano structures can be difficult due to the unavailability of nanowire structures. Wire-like nano structures have attracted extensive interest over the past decade due to their great potential for addressing some basic issues about dimensionality and space confined transport phenomena as well as related applications. In geometrical structures, these nanostructures can be classified into two main groups: hollow nanotubes and solid nanowires, which have a common characteristic of cylindrical symmetric cross-sections. Besides nanotubes, many other wire-like nanomaterials, such as carbides, nitrides, compound semiconductors, element semiconductors, and oxide nanowires have been successfully fabricated.
However, the nanostructures discussed above can have a variety of deficiencies. For example, often it is difficult to control the structure and morphology of many nanostructures. Further, many nanostructures are not defect and/or dislocation free. These deficiencies can cause problems such as, for example, uncontrolled properties due to uncontrolled structure and morphology, scattering from dislocations in electric transport applications, and degraded optical properties.
Semiconducting oxides, as an important series of materials candidates for optoelectronic devices and sensors, have attracted considerable attention in scientific research and technological applications. Recently, quasi-one-dimensional nanostructures for the functional materials have been successfully fabricated by using various approaches including thermal evaporation, sol-gel, arc discharge, laser ablation and template-based method. To date, extensive research work has been focused on ZnO, which is one of the most useful oxides for optical and sensor applications. Many different morphological ZnO nanostructures, including wires, belts, and rods, etc., have been fabricated.
In ZnO, a combination of the three types of fast growth directions ([2 1 10], [01 10], and [0001]) and the three area-adjustable facets [2 1 10], [01 10], and [0001]) of ZnO has resulted in a diverse group of hierarchical and intricate nanostructures. In addition to non-central symmetry, the semiconducting and piezoelectric as well as surface polarization characteristics of ZnO make it one of the most exciting oxide nanostructures for investigating nano-scale physical and chemical properties. Structural configurations such as piezoelectric nanobelts, nanosprings, and nanorings, etc., are known.
Certain patterned nanostructures have utility in many different applications, including electronics, optics and size differentiation of various particles. Unfortunately, such patterned nanostructures may be difficult to make at a large scale.
Therefore, there is a need for a method of making patterned nanostructures at a large scale.
There is also a need for patterned nanostructures.